Republican Warren G. Harding won 60.32 percent of the popular vote in the 1920 Presidential election, with a margin of victory over Democrat James M. Cox of 26.17 percent. Harding swept the Northeast, Midwest and West, losing only the Democratic Solid South.
Republicans were the normal U.S. majority party from 1900 through 1928. They won six of eight U.S. Presidential elections.
Incumbent Democratic President Franklin D. Roosevelt won 60.8 percent of the popular vote in the 1936 Presidential election, with a margin of victory over Republican Alfred E. Landon of 24.26 percent. Roosevelt swept the country except for two New England states, giving rise to the quip, “As Maine goes, so goes Vermont.”
Roosevelt’s New Deal made the Democrats the majority party. They won six out of the eight Presidential elections from 1932 through 1964.
Incumbent Democratic President Lyndon Johnson won 61.05 percent of the popular vote in the 1964 Presidential election, with a margin of victory over Republican Barry Goldwater of 22.58 percent. Johnson carried every state that Harding carried except one, but lost five Deep South states that went Democratic in 1920.
The Democratic majority seemed shaky after Republican Dwight D. Eisenhower won the Presidency in 1952 and 1956, and Democrat John F. Kennedy won with less than a 1 percent margin in the popular vote in 1960. But Democrat Lyndon Johnson won a landslide when he convinced voters that his opponent threatened the New Deal gains.
Incumbent Republican President Richard M. Nixon won 60.67 percent of the popular vote in the 1972 Presidential election, with a margin of victory over Democrat George McGovern of 23.15 percent. Nixon swept the country except for Massachusetts and the District of Columbia.
Nixon restored the Republican Party to majority status in Presidential elections. Republicans won five out of the six Presidential elections from 1968 through 1988.
Incumbent Republican President Ronald Reagan won 58.77 percent of the popular vote in the 1984 Presidential election, with a margin of victory over Democrat Walter Mondale of 18.21 percent. Reagan swept the country except for Minnesota and the District of Coluumbia. in 1984.
Reagan’s victory appeared to consolidate the Republican Party as the majority party. Yet from 1992 on, political power see-sawed between Republicans and Democrats. In 1992, 1996 and 2000, neither the Democratic nor Republican candidate received 50 percent of the votes cast. Republican George W. Bush’s popular vote margin in 2004 was only 2.46 percentage points. Barack Obama’s margin in 2008 was a solid but less-than-landslide 7.27 percentage points.
My guess is that the margin in 2012 will be narrow. I think voters will continue to be dissatisfied with both parties until the leaders of one of them adequately address the nation’s economic problems.
Click on List of United States presidential elections by popular vote margin for the Wikipedia tabulation. The vote share of Democratic and Republican Presidential candidates doesn’t add up to 100 percent because they’re never the only candidates on every state’s ballot.